Drug Interactions between metoclopramide and Osmolex ER

GENERALLY AVOID: Metoclopramide may antagonize the pharmacologic effects of amantadine in the treatment of Parkinson's disease and drug-induced extrapyramidal reactions. Animal data suggest that amantadine may possess direct and indirect effects on dopamine neurons, and more recent studies have demonstrated that amantadine is a weak, noncompetitive NMDA (N-methyl-D-aspartate) receptor antagonist. In contrast, metoclopramide exhibits central antidopaminergic effects and augments NMDA activity. Adverse effects of metoclopramide include pseudoparkinsonism and extrapyramidal reactions, which are consistent with its pharmacologic effects. Conversely, amantadine may antagonize the actions of metoclopramide on the gastrointestinal tract due to its anticholinergic effects.

MANAGEMENT: Patients receiving amantadine for Parkinson's disease or drug-induced extrapyramidal reactions should generally avoid antidopaminergic agents including metoclopramide. If these agents have been administered together chronically, amantadine dosing should not be abruptly reduced or discontinued due to the potential to precipitate a parkinsonian crisis, delirium, agitation, delusions, hallucinations, paranoid reaction, stupor, anxiety, depression, slurred speech, and rarely, neuroleptic malignant syndrome. In patients receiving amantadine for influenza A prophylaxis or treatment, the possibility of diminished efficacy of metoclopramide should be considered during coadministration.